Chestnut blight is a fungal disease caused by the pathogen Cryphonectaria parasitica, which affects American chestnut trees. This disease leads to the formation of cankers on the tree's bark, disrupting its ability to transport nutrients and water. As a result, infected trees often die within a few years of infection. The blight was first identified in the early 1900s and has since devastated chestnut populations in North America. Efforts to combat the disease include breeding blight-resistant hybrids and exploring biological control methods to restore the once-dominant chestnut trees in their native habitats.